Linked Life Data

11015219

Source:http://linkedlifedata.com/resource/pubmed/id/11015219

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
40
pubmed:dateCreated
2000-11-1
pubmed:abstractText
The three-dimensional structure of a possible intermediate in the hydration reaction of cyanamide to urea catalyzed by human carbonic anhydrase II (hCAII) has been determined by cryocrystallographic techniques. The crystal structure shows that two different adducts are formed under the experimental conditions and that they have different occupancy in the crystal. The high occupancy form consists of a binary hCAII-cyanamide complex where the substrate has replaced the zinc-bound hydroxide anion present in the native enzyme, maintaining the tetrahedral geometry around the metal ion. The second, low-occupancy form consists of a hCAII-cyanamide-water ternary complex where the catalytic zinc ion, still being bound to cyanamide, is approached by a water molecule in a five-coordinate adduct. While the first form can be considered a nonproductive complex, the second form may represent an intermediate state of the catalyzed reaction where the water molecule is about to perform a nucleophilic attack on the zinc-activated cyanamide substrate. The structural evidence is consistent with the kinetic data previously reported about this recently described hydrolytic reaction catalyzed by hCAII, and indicates that a different mechanism with respect to that generally accepted for the physiologic carbon dioxide hydration reaction may be adopted by the enzyme, depending on the substrate chemical properties.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
10
pubmed:volume
39
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
12391-7
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Mechanism of cyanamide hydration catalyzed by carbonic anhydrase II suggested by cryogenic X-ray diffraction.
pubmed:affiliation
Dipartimento di Chimica, Università di Siena, Via Aldo Moro, I-53100 Siena, Italy.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't